This invention relates to vehicle navigation systems and, more specifically, to map images appearing on a navigation system video screen of a display device.
Vehicle navigation systems typically include a display device with a video display that provides a graphical interface for the user. A main function of the video display is to depict the desired map area and route on which the user's vehicle is travelling. The map area shows various cartographic features, such as lakes and golf courses, to increase the utility to the user. These cartographic features are represented by cartographic entities that convey the nature of the cartographic feature so that the user may easily interpret it. For example, a solid green body may be used to represent a golf course and a solid blue body may be used to represent a lake. The map area shown on the video display may have numerous cartographic entities displayed making the vehicle route, which is typically the user's primary interest, more difficult to identify. That is, the shear number of cartographic entities displayed on the video display distracts the user and increases the amount of time it takes the user to locate the vehicle route on the video display. Additionally, displaying numerous cartographic entities increases the time it takes to regenerate or update the video display, which may cause an undesirable delay in displaying the updated information to the user as the vehicle moves across the map area. Furthermore, the intensity of the vehicle route and other roads in the map area are the same, making it difficult to quickly identify the vehicle route.
Depending upon the operational mode of the navigation system, it may be desirable to vary the intensity of certain roads and/or have fewer or less detailed cartographic entities displayed such as described above. However, in some operational modes it may desirable to display cartographic entities for all the cartographic features. Therefore, it is desirable to selectively display cartographic entities based upon the operational mode of the vehicle navigation system. In this manner, the user may be provided the desired level of map details and have the video display regenerated rapidly.